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NFS: Fix an unstable write data integrity race 

Commit 2c61be0a94 (NFS: Ensure that the WRITE
and COMMIT RPC calls are always uninterruptible) exposed a race on file
close. In order to ensure correct close-to-open behaviour, we want to wait
for all outstanding background commit operations to complete.

This patch adds an inode flag that indicates if a commit operation is under
way, and provides a mechanism to allow ->write_inode() to wait for its
completion if this is a data integrity flush.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
hifive-unleashed-5.1
Trond Myklebust 2010-04-22 15:35:57 -04:00
parent cdd29ecfcb
commit 71d0a6112a
2 changed files with 33 additions and 4 deletions
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36
fs/nfs/write.c
View File

@ -1201,6 +1201,25 @@ int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
static int nfs_commit_set_lock(struct nfs_inode *nfsi, int may_wait)
{
if (!test_and_set_bit(NFS_INO_COMMIT, &nfsi->flags))
return 1;
if (may_wait && !out_of_line_wait_on_bit_lock(&nfsi->flags,
NFS_INO_COMMIT, nfs_wait_bit_killable,
TASK_KILLABLE))
return 1;
return 0;
}
static void nfs_commit_clear_lock(struct nfs_inode *nfsi)
{
clear_bit(NFS_INO_COMMIT, &nfsi->flags);
smp_mb__after_clear_bit();
wake_up_bit(&nfsi->flags, NFS_INO_COMMIT);
}
static void nfs_commitdata_release(void *data)
{
struct nfs_write_data *wdata = data;
@ -1262,8 +1281,6 @@ static int nfs_commit_rpcsetup(struct list_head *head,
task = rpc_run_task(&task_setup_data);
if (IS_ERR(task))
return PTR_ERR(task);
if (how & FLUSH_SYNC)
rpc_wait_for_completion_task(task);
rpc_put_task(task);
return 0;
}
@ -1294,6 +1311,7 @@ nfs_commit_list(struct inode *inode, struct list_head *head, int how)
BDI_RECLAIMABLE);
nfs_clear_page_tag_locked(req);
}
nfs_commit_clear_lock(NFS_I(inode));
return -ENOMEM;
}
@ -1349,6 +1367,7 @@ static void nfs_commit_release(void *calldata)
next:
nfs_clear_page_tag_locked(req);
}
nfs_commit_clear_lock(NFS_I(data->inode));
nfs_commitdata_release(calldata);
}
@ -1363,8 +1382,11 @@ static const struct rpc_call_ops nfs_commit_ops = {
static int nfs_commit_inode(struct inode *inode, int how)
{
LIST_HEAD(head);
int res;
int may_wait = how & FLUSH_SYNC;
int res = 0;
if (!nfs_commit_set_lock(NFS_I(inode), may_wait))
goto out;
spin_lock(&inode->i_lock);
res = nfs_scan_commit(inode, &head, 0, 0);
spin_unlock(&inode->i_lock);
@ -1372,7 +1394,13 @@ static int nfs_commit_inode(struct inode *inode, int how)
int error = nfs_commit_list(inode, &head, how);
if (error < 0)
return error;
}
if (may_wait)
wait_on_bit(&NFS_I(inode)->flags, NFS_INO_COMMIT,
nfs_wait_bit_killable,
TASK_KILLABLE);
} else
nfs_commit_clear_lock(NFS_I(inode));
out:
return res;
}

1
include/linux/nfs_fs.h
View File

@ -209,6 +209,7 @@ struct nfs_inode {
#define NFS_INO_FLUSHING (4) /* inode is flushing out data */
#define NFS_INO_FSCACHE (5) /* inode can be cached by FS-Cache */
#define NFS_INO_FSCACHE_LOCK (6) /* FS-Cache cookie management lock */
#define NFS_INO_COMMIT (7) /* inode is committing unstable writes */
static inline struct nfs_inode *NFS_I(const struct inode *inode)
{